Require (3mm diameter x 2mm length) cylindrical neodymium magnets This is a copy of Zubits http://zubits.com/ Allow you to avoid unlacing/lacing shoelaces, the next best thing to velcros (^_^)b Print a set of 4, remember to mirror, holes might need clean up to fit flush and neat. Print 100% solid. Lacing is straightforward, lacing forward and backward to use up the extra lengths. FreeCAD file included